1. Field of the Invention
The present invention relates to a mobile communication service, and more particularly to a method of reporting a service option re-negotiation to a mobile switching center.
2. Background of the Related Art
Generally, when an call (i. e., originating/terminating call) is established in a related art CDMA mobile communication system, the service option negotiated between a mobile station (MS) and a base station is reported to a mobile switching center.
Specifically, if a mobile station wants to receive a specific service, it requests the base station a service option corresponding to that service in an initial call setup procedure. Then the base station and the mobile switching center assign the required resources to provide the specified service to the mobile station according to the service option negotiated with the mobile station.
In the call (i. e., originating/terminating call) setup procedure between the mobile station and the base station, the mobile station and the base station perform a service option negotiation procedure. Then the base station reports negotiated service option to the mobile switching center. The mobile switching center makes accounting information or creates a call detailed record(CDR) based on the service option information.
If the service option needs to be changed by the base station, for example due to base station's resource management, or by the mobile station during the conversation, a service option re-negotiation procedure can be performed. The service option re-negotiation is carried out in accordance with the communication standard for the signal process between the mobile station and the base station TIA/EIA IS-2000.5.
FIG. 1 illustrates a mobile communication system. Referring to FIG. 1, the mobile communication system comprises a mobile station (MS) 1, a base transceiver station (BTS) 21 and a base station controller (BSC) 22, namely base station, and a mobile switching center (MSC) 3. Communication between the mobile station 1 and the base station (21,22) is performed according to the IS-2000 standard. Communication between the base station 21,22 and the mobile switching center 3 is performed according to the 3G-IOS standard.
FIG. 2 illustrates the call set-up procedure of a CDMA mobile communication system. The procedure in the FIG. 2 focuses on the originating call setup procedure including service option negotiation process. Here, the service option negotiation procedure in FIG. 2 is also applied to the terminating call set-up procedure.
FIG. 3 illustrates the structure of a 3G-IOS Assignment Complete message including the service option determined through the call set-up procedure of FIG. 2. This message is transmitted from the base station to the mobile switching center. The message structure comprises a one (1) byte message type field, 301 for message discrimination, a channel number field 302, representing the channel number allocated, encryption information 303, representing encoding information of transmitted data, and a service option 304 representing service. The service option includes a service option information element identifier (IEI) 304′, and service option information 304″, representing value of the service option.
A related art originating call setup procedure will be described with reference to FIG. 2. First, when a user attempts to initiate a call, the mobile station transmits a TIA/EIA IS-2000 Origination message, including a service option so_A identifying the service required by the user. The origination message is transmitted to the base station on an access channel (step 201).
The base station, having received the IS-2000 Origination message, transmits an IS-2000 Acknowledgement Order to the mobile station (step 202). The base station then assigns a service option connection identifier (SOCI) (expressed by 1 byte to discriminate respective services) to the corresponding service. The SOCI is an identifier element for identifying the service provided between the base station and the mobile switching center. The base station transmits a 3G-IOS connection management (CM) service request message, including the service option so_A requested by the mobile station and corresponding SOCI to that service so_A, to the mobile switching center using a 3G-IOS complete layer 3 information message (step 203). The sending of this message drives a timer T303 for awaiting a 3G-IOS assignment request message from the mobile switching center (step 203).
Then the mobile switching center transmits a 3G-IOS Assignment Request message to the base station to request the assignment procedure for the radio resources (step 204). The sending of this message drives a timer T10 for a awaiting a 3G-IOS Assignment Completion message. The Assignment Request message terminates the timer T303. The base station and the mobile station then exchange a channel assignment message for the radio resource assignment process (i. e., traffic channel assignment process), a traffic preamble signal for matching the traffic channel synchronization, the base station sends Acknowledgment Order to acknowledge the traffic channel preamble, and the mobile station sends Acknowledgment Order (step 205).
After completion of the radio resources assignment procedure, the base station newly assigns a connection reference (CON_REF) defined in the TIA/EIAIS-2000.5 specification as an identifier for identifying the service between the mobile station and the base station. The base station then sends a Service Connection message to the mobile station, and the mobile station sends a Service Connection Completion message to the base station. These messages are used for determining a service configuration including the CON_REF Let's call it as CON_REF #1) and the corresponding service option so_A (step 206). And the service option could include “13k voice”, “8k enhanced voice rate control (EVRC)” in case of voice call to identify the kind of service and the quality of service.
According to the assignment request at step 204, the base station transmits to the mobile switching center the 3G-IOS Assignment Completion message, including the service option so_A determined through steps 205 and 206 (step 207). The mobile switching center, upon receiving this message, terminates the timer T10.
After the above described processes, the mobile station, base station, and mobile switching center enter into in a conversation state, and the mobile switching center uses the service option included in the 3G_IOS Assignment Completion message received from the base station for creation of the billing information or the CDR.
Subsequently, if the base station requires a change of the service option due to, for example, resource management of the system or a request of the mobile station during the conversation, a service option re-negotiation procedure can be performed according to the communication standard TIA/EIA IS-2000.5 between the mobile station and the base station (step 208).
When setting up the call, as described above, the service option negotiated between the mobile station 1 and the base station 21 and 22 is reported to the mobile switching center 3 using the 3GIOS Assignment Completion message as shown in FIG. 3. There ported information is used for reasons such as billing information.
When the service option of the call is changed through the service option re-negotiation procedure during the conversation, however, there is no way to report the change to the mobile switching center 3 currently. Instead, the mobile switching center can create the billing information or the CDR using only the service option negotiated during the call setup. Thus, the initially created information becomes inaccurate if service option re-negotiation procedure occurs during the conversation.
For example, if service option is changed from a 13k voice to a new value of 8k EVRC through service re-negotiation, there is no way for the base station to report the change of service option to the mobile switching center. Consequently, the data created based on only the service option negotiated during the call setup is incorrect.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.